Microsoft has made a change to an update for Windows 7 that can prevent certain systems from booting. While you might expect me to say, “good news, the software giant has fixed the problem”, in fact what Microsoft has done is switch the update from “optional”, to “recommended”. So, on some systems, it will now install, and break Windows 7 automatically .

There is good news though, and that’s you can solve the problem and get your computer working again by (can you guess?) upgrading to Windows 10. Hooray!
The update in question is KB3133977 and what this does is fix a problem that stops BitLocker encrypting drives because of service crashes in svhost.exe. If that’s a problem you have, you’ll welcome the fix.
Unless you have an ASUS motherboard.
As Microsoft explains:

After you install update 3133977 on a Windows 7 x64-based system that includes an ASUS-based main board, the system does not start, and it generates a Secure Boot error on the ASUS BIOS screen. This problem occurs because ASUS allowed the main board to enable the Secure Boot process even though Windows 7 does not support this feature.

This wasn’t much of a problem before because, as I say, the update was optional. But now it’s recommended, people are encountering this issue where they wouldn’t have done so previously. Woody Leonhard at InfoWorld says he’s seeing a
lot more problems being reported.

Microsoft also has a solution:
The Secure Boot feature is supported in Windows 10. To learn more about the security advantages of this feature and about the upgrade path from Windows 7 to Windows 10, go to the following Windows website: www.microsoft.com/windows